This invention relates to magnetic field sensors including split-drain or split collector transistors.
U.S. Pat. No. 3,714,559 discloses a magnetic field sensor comprising a "split-drain" MOS-transistor. U.S. Pat. No. 3,714,523 discloses a magnetic field sensor comprising a "split-drain/split gate" MOS-transistor. An article in IBM J. Res. Develop. Vol. 25, No. 3, May 1981, entitled "A Magnetic Sensor Utilizing an Avalanching Semiconductor Device" by A. W. Vinal discloses a magnetic field sensor comprising a "split collector" bipolar transistor.
The magnetic field sensors disclosed in the two U.S. patents referred to above have a degree of sensitivity which is too low for certain uses. In such a situation, they additionally require an amplifier connected to the output thereof, with the disadvantage that the effects of its offset voltage and its noise are added to the effects of those of the magnetic field sensor. Although the magnetic field sensor described by Vinal has a high degree of sensitivity, it is unstable because of its operating in the avalanche effect range and the resultant injection of hot charge carriers into the oxide.